It is conventionally known that a variable gear ratio steering (VGRS) device is capable of varying a ratio of a steered angle relative to a steering angle of a steering device. According to the following patent document 1, for example, a differential wheel mechanism and a variable gear ratio device are directly coupled to a shaft of a steering wheel provided as a steering device. The variable gear device has a gear ratio control motor, which drives the differential gear mechanism. It is recently also known that an electric power steering (EPS) device is used together with the VGRS device as a mechanism for assisting steering operation of a vehicle. The electric power steering apparatus is operated electrically to generate torque.    (Patent document 1) JP 2008-273327A
For example, if the steering assist operation of the EPS device stops due to, for example, its failure or the like, larger torque is required to operate a steering wheel than normally required. If the steering assist operation of the EPS device in a medium-sized or large-sized vehicle, which is heavy, it is sometimes almost impossible to operate the steering wheel. If such torque larger than the normal torque is required to operate the steering wheel, a driver will erroneously feel that the steering wheel is locked.